title: Changes in pH, acids, sugars and other quality parameters during extended vine holding of ripe processing tomatoes.
abstract: BACKGROUND
  Two important quality attributes of processing tomatoes are pH and titratable acidity. These and other quality attributes can be affected by tomato fruit maturity and over-maturity. We have determined the magnitude of these maturity effects in four processing tomato cultivars commonly grown in California.
  
  
  RESULTS
  Allowing tomatoes to remain on the vine for up to 4 weeks after ripening resulted in an increase in fruit pH of between 0.01 and 0.02 unit per day for the four cultivars examined. The increase in pH was paralleled by a decrease in titratable acidity, due to a loss of citric acid. Glucose and fructose concentrations also declined with increasing maturity after ripening. Other quality parameters (color, lycopene, total pectin, pectin solubility, and Bostwick consistency) all showed little change.
  
  
  CONCLUSIONS
  Vine holding of ripe fruit adversely affects quality, especially pH and titratable acidity. Recent problems with high tomato juice pH encountered by tomato processors in California could be the result of increased average fruit maturity at harvest.
authors.affiliation: Department of Food Science and Technology, University of California, Davis, CA 95616, USA. geanthon@ucdavis.edu
authors.forename: Gordon E
authors.initials: GE
authors.lastname: Anthon
authors.forename: Michelle
authors.initials: M
authors.lastname: LeStrange
authors.forename: Diane M
authors.initials: DM
authors.lastname: Barrett
mesh_terms: D000383:Agriculture / Q000379:methods*; D002140:California; D019343:Citric Acid / Q000378:metabolism*; D005511:Food Handling / Q000379:methods; D005632:Fructose / Q000378:metabolism*; D005638:Fruit / Q000254:growth & development / Q000378:metabolism* / Q000592:standards; D005947:Glucose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D019343:Citric Acid; D005632:Fructose; D005947:Glucose